1. Field of the Invention
The present invention relates generally to user charging in a mobile communication system. In particular, the present invention relates to a system and method of improving the charging of users for signaling generated for providing services that they have enjoyed.
2. Description of the Related Art
FIG. 1 is a block diagram illustrating the configuration of a conventional Universal Mobile Telecommunication System (UMTS) system.
Referring to FIG. 1, the UMTS system comprises User Equipments (UEs) which want particular services, a radio access part, and a Core Network (CN) part. The radio access part includes Node Bs and a Radio Network Controller (RNC) 105, and the CN part includes a Serving GPRS Support Node (SGSN) 110 and a Gateway GPRS Support Node (GGSN) 120. A mobile user can retrieve data from a data server of an external network, Packet Data Network (PDN) 130 over the UMTS network.
The SGSN 110 and the GGSN 120 collect information about the amount of traffic created for a specific Packet Data Protocol (PDP) context as charging information. The charging information that they collect includes a call duration, uplink data amount, downlink data amount, and Quality of Service (QoS) information.
The GGSN 120 provides services according to an Access Point Name (APN) identifying a server which will service a UE 100. The services include Simple Internet Protocol (IP), Layer Two Tunneling Protocol (L2TP), and Dynamic Host Configuration Protocol (DHCP) Relay. For the UE 100 to receive most of the services except the Simple IP service, GTP-U tunnels are first created between the RNC 105 and the SGSN 110 and between the SGSN 110 and the GGSN 120 and a PDP address is allocated to the UE 100 by additional signaling.
In the above conventional charging method, a Charging Gateway (CG) receives charging information separately from the SGSN 110 and the GGSN 120, and selects the charging information containing the smaller traffic amount as the final charging information for the user. The traffic amount included in the charging information collected by the SGSN and the GGSN also includes the amount of traffic caused by the additional signaling.
The inclusion of the additional signaling traffic in the charging information results in overcharging mobile users. Accordingly, a need exists for a method of synchronizing the start time of charging for actual user traffic between the SGSN and the GGSN.
In synchronizing the charging start, excluding signaling traffic accompanying a service in the GGSN leads to an overcharge calculated by the SGSN compared to the charge calculated by the GGSN. Therefore, the charging information of the SGSN is not adopted.
If the GGSN includes the signaling traffic in charging for the service, this results in a charge on the mobile user for signaling.